FAR INFRARED STUDIES ON STANNITE AND WURTZSTANNITE TYPE COMPOUNDS

Far-infrared and Raman spectroscopic studies were performed on compounds of composition A2BCX4 (A = Cu, Ag; B = Zn, Cd, Hg, Mn, Fe, Co; C = Si, Ge, Sn; X = S, Se) which crystallize in the stannite or wurtzstannite structure. Factor group analysis and deduction of Cartesian symmetry coordinates have been carried out for both structure types. The FIR spectra of numerous stannites and wurtzstannites are given and discussed according to the influence of the different metal ions. In the silicon compounds a quasi characteristic vibration of SiS4-tetrahedra is observed at 500 cm-1. Raman spectra of some stannites only show the two totally symmetric vibrations of species A1. These vibrations can be described as breathing modes of the BX4- and CX4-tetrahedra.